Bài 1:
$-201,6.0,4.(-25)$
$=-201,6.(-10)$
$=-2016$
Bài 2:
a) $\dfrac{3}{4}+\dfrac{2}{5}x=\dfrac{20}{60}=\dfrac{1}{3}$
$↔\dfrac{2}{5}x=\dfrac{1}{3}-\dfrac{3}{4}$
$↔\dfrac{2}{5}x=\dfrac{4}{12}-\dfrac{9}{12}=-\dfrac{5}{12}$
$→x=-\dfrac{5}{12}:\dfrac{2}{5}$
$→x=-\dfrac{5}{12}.\dfrac{5}{2}=-\dfrac{25}{24}$
b) $\begin{cases}|2-x|≥0\\|y+5|^2≥0\end{cases}$
$→$ Dấu "=" xảy ra khi $\begin{cases}2-x=0\\y+5=0\end{cases}$
$→\begin{cases}x=2\\y=-5\end{cases}$
$→A_\min=\dfrac{2020}{2021}$ khi $\begin{cases}x=2\\y=-5\end{cases}$
